I built the new catapult (that I talked about in my last post) and tested it.
Immediately I could see many of the improvements that were expected of the new design:
- It is easy to adjust.
- It fires straight.
- The turntable moves as expected (+/- 30 degrees).
- The new design is much easier to install on the robot.
However, I found that it was still too inconsistent. Specifically, the energy stored in the system would gradually decrease as the catapult was used for many shots. Initially I imagined that the rubber band was stretching and becoming weaker. But then I realised that the band was slipping along the catapult arm.
So here is the new design for the arm. It now incorporates a hole for the band to pass through so that it can’t slip along the arm.
I also found that there was insufficient travel in the trajectory adjuster. I went for the very high-tech approach of gluing on a piece of Lego to fix that:
This new (dare I say final) version is now yielding much better results. I’m optimistic it will achieve close to 15 out of 15 shots!